1. Field of the Invention
The present invention relates to an anode material for lithium secondary batteries and lithium secondary batteries.
2. Description of the Related Art
Since a lithium secondary battery is light weight and possesses a high output characteristic when compared with such as a nickel-hydrogen battery and a lead battery, a lithium secondary battery recently draws an attention as a high output power source for such as an electric vehicle and a hybrid type electric vehicle. For a lithium secondary battery used in a hybrid type electric vehicle, as its important factor, such a battery is desired that provides a high input and output, a high safety, a high initial charge and discharge efficiency and long lifetime characteristic at the same time.
In the past, although such as lithium metal and alloys were used as an active anode material used in the lithium secondary battery, since dendrite precipitates in accordance with repetition of cycles, cycle characteristic and safety are deteriorated, for this reason, carbon materials are recently studied actively as an alternative of the active anode materials.
From the past, many patents noticing the physical properties of the carbon materials have been issued. Patent document 1 discloses a carbon material having a structure in which volume of pores of not more than 5 nm in graphite occupies not less than 60% of the total volume of pores.
On one hand, patent document 2 discloses a carbon material in which a ratio of pore volumes is defined. Patent document 2 discloses a carbon material in which when assuming a volume of pores of 4˜10 nm is as V3 and a volume of pores of 30˜100 nm is as V4, V4/V3 is defined as 2.2˜3.0.    [Patent document 1] JP-A-9-7597    [Patent document 2] JP-A-2003-272625